The use of chemical reactions, in particular involving heterogeneous catalysis, in fixed bed reactors is known. When these chemical reactions are highly endothermic or highly exothermic, control of the heat absorbed or emitted by the reaction presupposes that the reactor has available extensive heat-exchange surfaces.
For example, a conventional geometry of fixed bed chemical reactors is the multitubular geometry. This geometry exhibits in particular the disadvantage of involving relatively complex and lengthy operations for charging and discharging catalyst which result in losses in productivity. Furthermore, multitubular reactors exhibit a very high manufacturing cost but also a very high weight related to the masses of metals which it is necessary to use. Another constraint on these reactors is related to their method of manufacture and transportation: they are limited in size as, manufactured and tested in a factory, they subsequently have to be transported to the site of final use.
Another geometry known for these reactors is the plate geometry. In a plate reactor, the reaction compartments are delimited by heat-exchange plates. The documents EP 0995491 and EP 1147807 provide examples of such plate reactors.
Another example appears in the document US 2005/0020851, which describes such a reactor used for the oxidation of a C3 or C4 precursor to give acrolein, methacrolein, acrylic acid or methacrylic acid.
The document US 2005/0158217 also describes a reactor of this type, in which thermocouples are positioned in the reaction compartments (without passing through them) in order to control the reaction.
The document US 2005/0226793 describes a specific arrangement of heat-exchange plates, in which arrangement the projections of each plate are facing the reinforcements of the adjacent plate and vice versa, in order to improve the control of the temperature.
Finally, the document US 2006/0276334 provides another example of a reactor of this type, in which the heat-exchange plates comprise a cracked coating (deposit).
All the above reactors exhibit the disadvantage of not making possible sufficient control/management of the temperature in the reactor, in the reaction phase and/or in the regeneration phase.
There thus exists a real need to make possible better control of the temperature in fixed bed reactors.